Fans having radial flow rotors in axial flow casings



Nov. 20, 1962 R. CARLSON 3,064,879

FANS HAVING RADIAL FLOW ROTORS IN AXIAL FLOW CASINGS Filed April 5, 1961 2 Sheets-Sheet l [www.- Bqgmoaadl. Whoa,

flii'oflnegg I Nov. 20, 1962 r R. L. CARLSON 3,

FANS HAVING RADIAL FLOW ROTORS IN AXIAL mow CASINGS Filed April 3, 1961 2 Sheets-Sheet 2 F ,tg: a

132191282308 Haymond 1;. caflwoaal,

69 W a M uqffzrvneg 3,064,33 Patented Non. 2Q, 1952;,

3,064,879 FANS HAVING RADIAL FLOW RGTURS IN AXIAL FLGW CASENGS Raymond L. Carlson, Canton, Mass, assi@or to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 3, 1961, Ser. No. 100,059 6 Claims. (Cl. 230-127) This invention relates to fans having centrifugal rotors, and relates more particularly to fans having centrifugal rotors within axial flow casings.

In fans having centrifugal rotors within axial flow casings, it is customary to support the shafts of the rotors and the bearings for the shafts, within inner casings behind the rotors. Such fans are often used to handle hot and contaminated gases which may overheat the bearings, and which may escape into the rooms in which the fans are supported.

An object of this invention is to cool the bearings of fans.

Another object of this invention is to prevent gas handled by a fan from leaking into the room in which the fan is supported.

This invention will now be described with reference to the annexed draw ngs, of which:

FIG. 1 is a side section of a fan embodying this invention;

FIG. 2 is an enlarged fragmentary side section of a modification of FIG. 1, embodying this invention, and

FIG. 3 is an enlarged fragmentary side section of another modification of FIG. 1, embodying this invention.

Referring to the drawings, a generally cylindrical outer casing has its upstream or front end wall 11 turned inwardly to form an inwardly converging, conical gas inlet passage 12 connected to a gas supply duct 13. The casing 10 has at its back or downstream end, a converging wall 14 formed as a frustrum of a cone. The downstream end of the wall 14 is connected to an outlet duct 14. The casing 10 is supported on a base 16-.

An inner casing 17 has a cylindrical upstream portion 18 and a converging downstream wall 19 shaped as a frustrum of a cone, supported from and concentric with the outer casing 10 by spin removing vanes 20 within an annular passage 21 between the cylindrical portions of the inner and outer casing. The walls 14 and 19 are concentric with the wall 19 converging more than the wall 14 so as to form a diverging passage 23 between the walls 14 and 19.

Supported on rails 24 which extend horizontally across the interior of the inner casing 17, and are secured at their ends to the interior surface of the Wall 18, are bearings 27 for hollow rotary shaft 28. The shaft 28 has attached to its outer end hub 30 of centrifugal rotor 31 having blades 32 secured to a back plate 33 and a front plant 34 of conventional construction. The rotor 31 has an axial inlet between the outer end of its front plate 34 and the inner end of the passage 12. The back plate 33 is secured to the hub 30 by rivets 36. A pulley 37 is attached to the downstream end of the shaft 28.

The inner casing 17 has a downstream end which is closed by end Wall 38, and has an upstream end which is closed by end wall 39 which has a clearance opening for the downstream end of the hub 30, the wall 39 extending parallelto and spaced axially from the back plate 33 of the rotor 31.

An electric motor 40 has a base 41 attached to the top of the casing 10, and has a pulley 42 on its shaft 43, aligned vertically with the pulley 37. The walls 14 and 19 have a hollow fairing 45 extending therethrough, vertically aligned with the pulleys 37 and 42. Belts 47 on the pulleys 37. and 42 extend through the fairing 45.

The hollow shaft 28 may have a spiral sheet 49 extending therein, the length thereof, and which acts as an auxiliary fan. i

in the operation of FIG. 1, the rotor 3-1, rotated by the motor 40, draws gas through the duct 13 and passage 12, and discharges it radially in a spiral. The gas discharged from the rotor is turned axially by the inner and outer casings 17 and 19 respectively, and passes through the annular passage 21. Near the downstream end of the passage 21, the spin removing vanes 2t) remove the spin from the gas recovering pressure therefrom, the straightened-out gas passing through the passage 23 into the outlet duct 15.

With this type of fan, for aerodynamic reasons, it is customary to place the shaft bearings within the inner casing 17 which is closed except for the connection of its interior through the hollow fairing to the atmosphere around the fan, and except for the small clearance opening in its end wall 39 around the hub 30, and which may con-' tain a seal which may leak. When 'hot gas passes through the annular passage 21, the interior of the inner casing may be so heated that the bearings 27 may be damaged. For preventing this, the hollow shaft 28 is provided. Without the spiral sheet 49 within the shaft, the pressure of the air around the fan is greater than the gas pressure at the center of the rotor, so that air Will be drawn in through the interior of the fairing 45, into the interior of the inner casing 17, then into the shaft'28, cooling the bearings 27, then into the fan rotor 31 which discharges it, with the gas from the passage 12, into the annular passage 21, as shown by the arrows on FIG. 1. When gases having very high temperatures are handled, the spiral sheet 49 can be added for increasing the volume of air passed through the hollow shaft, thereby increasing the cooling of the bearings.

Gas handled by the fan may escape through the opening through the wall 39 around the hub 30, even when a seal is placed in this opening. This invention prevents such leaking gas which may be toxic, from passing through the fairing 45 into the room where the fan is located, by recirculating it through the rotor.

FIG. 2 shows how FIG. 1 can bemodified by using a fan rotor shaft 28A which is solid except at its inner portion 50 which is hollow where it passes through upstream end Wall 39A of the inner casing, and through hub 30A of the fan rotor, forming an axial passage '51, the wall of the shaft around this passage having spaced-apart, circular openings 52 extending therethrough between the end wall 39A of the inner casing 17, and the rotor back plate 33. The wall 39A has a circular opening 56 around the shaft 28A, and has secured thereto a seal ring 57 forming a nozzle which extends through the opening 56 around the shaft 28A into the space between the wall 39A and the back plate 33, and which converges towards the hub 30A. Attached to the hub 39A is a ring 58 which extends around the inner end of the nozzle 57. The hub 30A has threaded therein around the inner end of the shaft 28A, screws 58 around which extend spacers 59, a deflector disc 69 being supported between the ends of the spacers 59 and the heads of the screws '58.

In the operation of FIG. 2, the lower pressure at the center of the rotor causes air to flow from the inner casing through the nozzle 57 into the shaft openings 52 and through the shaft passage 51 into the center of. the rotor. The difference in pressure also causes any gas leaking into the space between the back plate 33 and the inner casing wall 39A to flow through the space between the ring 58 and the nozzle 57 into the shaft openings 52 and shaft passage 51 into the center of the rotor. The defiector disc 60 deflects the indrawn air and gas radially towards the rotor blades.

FIG. 3 shows a modification of FIG. 2 in which the shaft openings 52 are aligned with the opening 56 in the wall 39A, and in which instead of using the nozzle 57 and ring 58 of FIG. 2, the wall 39A has a ring 62 attached to its outer side and a similar ring 63 attached to its inner side, around and with their inner ends spaced from the shaft 28A.

In the operation of FIG. 3, air drawn from the inner casing passes through the space between the inner end of the ring 62 and the shaft, into the shaft openings 52 and shaft passage 51 into the center of the fan rotor, and any gas between the back plate 33 and the wall 39A, is drawn through the space between the inner end of the ring 63 and the shaft 28A, into the shaft openings 52 and shaft passage 51 into the center of the rotor.

-In FIGS. 2 and 3, the flow of air from the inner casing into the shaft passages 51 passes over the bearings of the shaft 28A for cooling them, and forms air seals preventing the gas handled by the rotor from flowing into the inner casing.

What is claimed, is:

l. A fan comprising an outer casing, circular in section, a smaller inner casing, circular in section, within said outer casing, spaced therefrom and concentric therewith, said inner casing having a closed downstream end wall, and having an upstream end wall having an opening around the axis of said casings, a centrifugal fan rotor within said outer casing and having a back plate upstream of, adjacent to and extending substantially parallel to said upstream wall, said rotor having a front plate spaced from said back plate and having fan blades supported between said plates, means forming an axial inlet passage into said rotor, said rotor discharging into the space between said casings, a shaft attached to said back place and extending through said opening around said axis, bearings within said inner casing around said shaft, said shaft having an axial passage therein where it passes through said opening, said shaft passage opening into the center of said rotor between the inner ends of said blades, said shaft passage communicating with the interior of said inner casing, and means extending through said outer casing, through said space between said casings and into said inner casing for the passage of air from around said outer casing into said inner casing, the lower pressure at the center of said rotor causing air to be drawn in through said means into said inner casing and through said passage into said center of said rotor.

2. A fan comprising an outer casing, circular in section, a smaller inner casing, circular in section, within said outer casing, spaced therefrom and concentric therewith, said inner casing having a closed downstream end wall, and having an upstream end wall with a central opening around the axis of said casings, a centrifugal fan rotor within said outer casing and having a back plate upstream of, adjacent to and extending substantially parallel to said upstream wall, said rotor having a front plate and having fan blades supported between said plates, means forming an axial inlet passage into said rotor, said rotor discharging into the space between said casings, a hollow shaft attached to said back plate and extending through said opening around said axis, bearings within said inner casing around said shaft, said shaft opening at one end within said inner casing and at its other end within the center of said rotor between the inner ends of said blades, and means extending through said outer casing, through said space between said casings and into said inner casing for the passage of air from around said outer casing into said inner casing, the lower pressure at the center of said rotor causing air to be drawn in through said means into the interior of said inner casing and through said hollow shaft into said center of said rotor.

3. A fan comprising an outer casing, circular in section, a smaller inner casing circular in section, within said outer casing, spaced therefrom and concentric therewith, said inner casing having a closed downstream end wall and having an upstream end wall with a central opening around the axis of said casings, a centrifugal fan rotor within said outer casing and having a back plate upstream of, adjacent to and extending substantially parallel to said upstream wall, said rotor having a front plate and having fan blades supported between said plates, means forming an axial inlet passage into said rotor, said rotor discharging into the space between said casings, a hollow shaft attached to said back plate and extending through said opening around said axis, bearings within said inner casing around said shaft, said shaft opening at one end within said inner casing and at its other end within the center of said rotor between the inner ends of said blades, means extending through said outer casing, through said space between said casings and into said inner casing for the passage of air from around said outer casing into said inner casing, and means within said hollow shaft forming an auxiliary fan for drawing air through said means into said inner casing and into said shaft and for discharging the air through said shaft into the center of said rotor.

4. A fan comprising an outer casing, circular in section, a smaller inner casing, circular in section, within said outer casing, spaced therefrom and concentric therewith, said inner casing having a closed downstream end wall, and having an upstream end wall with a circular opening around the axis of said casings, a centrifugal fan rotor within said outer casing and having a back plate, upstream of, adjacent to and extending substantially parallel to said upstream wall, said rotor having a front plate spaced from said back plate and having fan blades supported between said plates, means forming an axial inlet passage into said rotor, said rotor discharging into the space between said casings, a shaft extending at one end into the center of said rotor, attached to said back plate and extending through said opening around said axis into said inner casing, said shaft having a portion that is hollow from where it passes through said opening to said one end, and having spaced-apart openings extending where it is hollow through its wall into the hollow interior thereof, a seal ring having an outer end attached to said upstream end wall around said circular opening and having an inner end spaced closer to said shaft than the edge of said upstream wall around said circular opening, and means extending through said outer casing, through said space between said casings and into said inner casing for the passage of air from around said outer casing into said inner casing, the lower pressure at the center of said rotor causing air to be drawn in through said means into said inner casing and through the space between said inner end of said seal ring and said shaft and through said spacedapart openings and said hollow shaft portion into said rotor center.

5. A fan comprising an outer casing, circular in section, a smaller inner casing, circular in section, within said inner casing, spaced therefrom and concentric therewith, said inner casing having a closed downstream end wall, and having an upstream end Wall with a circular opening around the axis of said casings, a centrifugal fan rotor within said outer casing and having a back plate, upstream of, adjacent to and extending substantially parallel to said upstream wall, said rotor having a front plate spaced from said back plate and having fan blades supported between said plates, means forming an axial inlet passage into said rotor, said rotor discharging into the space between said casings, a shaft extending at one end into the center of said rotor, attached to said back plate and extending through said opening around said axis into said inner casing, said shaft having a portion that is hollow from where it passes through said opening to said one end, and having spaced-apart openings extending through its wall into the hollow interior thereof where it passes through said circular opening, a pair of seal rings having outer ends attached to the upstream and downstream sides of said upstream wall around said circular opening and having inner ends spaced closer to said shaft than the edge of said upstream wall around said opening, and means extending through said outer casing, through said space between said casings and into said inner casing for the passage of air from around said outer casing into said inner casing, the lower pressure at said rotor center causing air to be drawn in through said means into said edge of said ring attached to said downstream side of said upstream wall and said shaft and through said spacedapart openings and said hollow shaft portion into said rotor center, any gas passing from said rotor into the space between said back plate and said upstream wall being drawn by the lower pressure at said rotor center through the space between the inner edge of said ring attached to said upstream side of said upstream wall, through said spaced-apart openings into said hollow shaft portion and through said hollow shaft portion into said rotor center.

6. A fan comprising an outer casing, circular in section, a smaller inner casing, circular in section, within said outer casing, spaced therefrom and concentric therewith, said inner casing having a closed downstream end wall, and having an upstream end wall with a circular opening around the axis of said casings, a centrifugal fan rotor within said outer casing and having a back plate upstream of, adjacent to and extending substantially parallel to said upstream wall, said rotor having a front plate spaced from said back plate and having fan blades supported between said plates, means forming an axial inlet passage into said rotor, said rotor discharging into the space between said casings, a hub for said rotor extending through and attached to said back plate, a shaft extending through and attached to said hub and having one end extending into the center of said rotor, and extending around said axis through said circular opening into said inner casing, said shaft having an upstream portion that is hollow from it extends through said circular opening to said one end, and having spaced-apart openings extending through its wall into the hollow interior thereof, a first seal ring having an outer end attached to the downstream side of said upstream wall around said circular opening, and having a converging inner ring portion extending through said circular opening around and spaced from said hollow shaft portion into the space between said back plate and said upstream wall, a second seal ring having its outer end attached to the downstream side of said hub around said hollow shaft portion, and having its inner end extending around the inner end of said first ring and spaced therefrom, and means extending through said outer casing, through said space between said casings and into said inner casing for the passage of air from around said outer casing into said inner casing, the lower pressure at said rotor center causing air to be drawn through said means into said inner casing, through the space between said inner ring portion of said first ring, through said spaced-apart openings into said hollow shaft portion and through said hollow shaft portion into said rotor center, any gas passing from said rotor into the space between said back plate and said upstream wall passing through the space between said inner ends of said rings, through said spaced-apart openings into said hollow shaft portion and through said hollow shaft portion into said rotor center.

References Cited in the file of this patent UNITED STATES PATENTS 390,508 Mosher et a1. Oct. 2, 1888 1,429,538 Schetzel Sept. 19, 1922 2,469,820 Fuge May 10, 1949 2,601,030 Klein et a1. June 17, 1952 2,888,188 Hersh May 26, 1959 FOREIGN PATENTS 229 Great Britain of 1904 133,518 Australia July 14, 1949 339,017 Germany July 11, 1921 1,016,738 France Apr. 26, 1950 

